Fundamentals of RPD Design

Question 1

which kennedy classification cannot have a modification space

Answer 1

class IV

Question 2

what are the tooth-tissue supported kennedy classifications

Answer 2

• kennedy class I (Bilateral distal extension)
• kennedy class II (unilateral distal extension)

Question 3

what are the tooth supported kennedy classifications

Answer 3

• kennedy class III
• kennedy class IV (single edentulous area crossing the midline)

Question 4

what is after determining the class of the RPD

Answer 4

• survey the cast and draw/carve orientation (tripod) lines
• draw heights of contour
• evaluate possible guide planes
• identify undercuts

Question 5

what are the mandibular major connectors

Answer 5

• lingual plate
• lingual bar

Question 6

what are the 5 reasons to lingual plate

Answer 6

• opposing a maxillary denture
• inadequate space for a bar (8mm needed)
• anticipate loss of additional teeth
• mandibular tori
• aid in lateral and rotational stability

Question 7

what are the maxillary major connectors

Answer 7

• palatal strap
• anterior palatal strap
• A-P strap
• full palatal coverage

Question 8

if the major connector is not plating the lingual surfaces of the max teeth the frame needs to be:

Answer 8

at least 6mm away from the gingival margin

Question 9

the minor connectors are:

Answer 9

portion of the RPD framework that connects the major connector to the clasp assembly, indirect retainer, denture base

Question 10

in a kennedy class III RPD the rests of the RPD are located where

Answer 10

toward the edentulous area on the teeth adjacent to the edentulous area

Question 11

you need approximately _____ of inter occlusal clearance

Answer 11

1.5mm

Question 12

RPD rests are ____ of the buccal/lingual width

Answer 12

1/3

Question 13

RPD rests in an edentulous area bordered by teeth on anterior and posterior rests are located _____ the edentulous space

Answer 13

toward

Question 14

where are RPD rests located in a free end distal extension

Answer 14

away from the edentulous area

Question 15

how many retentive clasps would be used in a kennedy class I design

Answer 15

2

Question 16

what are the number of clasps necessary for a kennedy class I

Answer 16

2

Question 17

what are the number of clasps necessary for a kennedy class II

Answer 17

3

Question 18

what are the number of clasps necessary for a kennedy class III and IV

Answer 18

4

Question 19

how do you alter the retentiveness of a clasp

Answer 19

• clasp length
• clasp diameter
  -clasp taper
• 1/2 round or round
• material
• amount of undercut engaged

Question 20

what are the two types of retentive clasps

Answer 20

• infrabulge
• suprabulge

Question 21

what are the infrabulge clasps

Answer 21

• I-bar clasps
• T and 1/2 T clasp
• Y clasp

Question 22

what are the suprabulge clasps

Answer 22

• cast circumferential clasp (1/2 round and round)
• wrought wire (combination clasp)

Question 23

what are the advantages of infrabulge clasps and contra indications

Answer 23

• advantages: esthetic, more retentive
• contra indications: excessive soft tissue undercut, lack of vestibular depth (min 4 mm), inability to place the terminus at the gingival 1/3

Question 24

where are infrabulge clasps best utilized

Answer 24

on a sound abutment tooth adjacent to a free end edentulous area provided the tooth is tall enough and provides relief (undercut) gingival to the distal guide plate

Question 25

what are the circumferential suprabulge clasps

Answer 25

1/2 round or round cast

Question 26

what are the best utilized suprabulge

Answer 26

1/2 round - tooth supported RPDs - round - tooth/tissue supported RPDs

Question 27

wrought wire clasps are also called

Answer 27

combination clasps

Question 28

when are wrought wire clasps best used

Answer 28

on tooth/tissue supported RPDs when the abutment tooth is compromised and an ideal guide plane is not present

Question 29

where will rest seats be with with tooth/tissue supported RPDs when the abutment tooth is comproised and an ideal guide plane is not present

Answer 29

toward the free end distal extension

Question 30

what if you dont have any undercut

Answer 30

- surveyed crown - place a divot - place composite

Question 31

what if you dont have a buccal undercut

Answer 31

lingual retentive clasps

Question 32

when an RPD is completely seated what is the function of the reciprocal clasp

Answer 32

it serves no purpose when fully seated

Question 33

what is the reciprocal used for

Answer 33

to counterbalance the forces applied by the retentive clasp as it passes over the height of contour

Question 34

what is the action distance of sterm

Answer 34

the distance that in which the retentive clasp is reciprocated - 3-5mm

Question 35

where are reciprocal clasps located

Answer 35

on all teeth that have a retentive clasp

Question 36

which kennedy classification will never have an indirect retainer

Answer 36

class IV

Question 37

what are the types of indirect retainers

Answer 37

- occlusal - incisal - cingulum

Question 38

where are indirect retainers located

Answer 38

on tooth tissue supported RPDs

Question 39

indirect retainers are located _______ to the primary fulcrum line which extends through _________

Answer 39

anterior; the most posterior abutments

Question 40

what is the purpose of the indirect retainer

Answer 40

resists the RPDs tendency to move or rotate in an occlusal direction

Question 41

what are the RPD impression techniques

Answer 41

static and functional impressions

Question 42

PDL of abutment has a vertical displacement of ______

Answer 42

0.25mm

Question 43

the gingival tissue on the residual ridge has a vertical displacement of about _____

Answer 43

2mm

Question 44

what are the RPD impression methods

Answer 44

- metal stock tray with alginate (never plastic) - custom tray, border mold, PVS impression - corrected (altered) cast impression

Question 45

when are the altered cast impressions done

Answer 45

on mandibular kennedy class I and II

Question 46

describe the impression technique

Answer 46

framework must fit the mouth and be passive - add tray to framework -1mm wax relief - check seating on cast and in mouth - after tray is added: rests must be fully seated also the major connector, no resistance to seating - check peripheries - border molding

Question 47

impression tray must be _____ short of vestibular extend

Answer 47

2-3mm

Question 48

no displacement when:

Answer 48

pulling on the cheeks and lips - patient activates the tongue

Question 49

border molding techniques are ______ for RPD as CD

Answer 49

the same

Question 50

how do you do the corrected cast impression

Answer 50

- remove wax spacer - coat tray with adhesive - use light body impression material - carefully load tray - no material under rests, guide planes, major connector - seat with pressure only over the rests, not on the saddle

Question 51

why dont you want pressure over the tray

Answer 51

will cause tissue compression

Question 52

what should be inspected on the impression

Answer 52

- no material under rests or minor connectors- remove excess material if present - impression detail is correct

Question 53

what are the lab steps

Answer 53

- section cast- remove extensions - place retentive grooves or holes in the master cast - ensure no contact between impression material/tray and cast - sticky wax framework in place against teeth

Question 54

describe boxing technique

Answer 54

box the master cast with the RPD framework/impression attached and pour the new edentulous ridges in yellow stone

Question 55

what do you add if the metal stops dont contact the cast

Answer 55

add duralay tissue stops to the framework

Question 56

what are the potential problems with the corrected cast technique

Answer 56

- a framework not seated either during the impression (material under rest, plate) or when being poured will result in an RPD that wont fit properly on teeth/tissues - stone leaking over teeth during pouring makes articulation impossible